The rape and murder of 27-year-old rising punk-rock star Mia Zapata, lead singer of "The Gits," remained unsolved for nine years despite a case file that detectives described as "voluminous" and an investigation they deemed exhaustive.

Seattle's grunge rock community raised $70,000 to hire a private investigator. Friends kept her memory alive and in the news by writing songs and founding a nonprofit organization that teaches self-defense. "America's Most Wanted" aired a segment on her murder.

Yet none of the leads generated by all this attention led to the arrest of Jesus Mezquia, a 48-year-old Florida fisherman with a history of sexual assaults, who police say sexually assaulted and strangled Zapata then left her dead on a deserted Seattle street in the early morning of July 7, 1993.

Instead, investigators found their suspect thanks to well-preserved swabs of saliva taken from the victim's body, a knowledgeable Florida parole officer and a DNA match.

"There was nothing that identified Mezquia as a suspect," said Seattle Police Department spokesman Duane Fish. "Subsequently, we've been able to link him to the area, even to the neighborhood where the murder occurred. But that's all with hindsight, which is 100 percent available due to the DNA hit."

Mezquia had lived in Seattle only briefly and, contrary to earlier theories of Zapata's murder, seems to have had no personal connection with the late singer or her music.

The case is one of the hundreds of unsolved murders in the U.S. that are being reinvigorated, not through investigative leads, but through DNA matches, known as a "cold hits." While DNA typing has been available for at least a decade, the increased accuracy of DNA analysis, improved extraction techniques and the creation of a nationwide database have allowed investigators who have nothing but a small amount of biological evidence from the crime scene to find strong suspects.

Technology has advanced so much that technicians now need only trace amounts of DNA to generate a complete profile. In the Zapata case, Seattle investigators did not recover any semen from the crime scene.

"With older cases saliva was not something you would first look for, you'd look for blood or semen," says Detective Gregg Mizsell, one of the two investigators on the cold case squad who broke the case. "So it was with a lot of foresight that the county examiner swabbed her breasts."

This is the first time King County has successfully developed a DNA profile from saliva. Five years ago, authorities would not even have bothered to submit a sample that small for testing.

Faster, easier, more accurate

Of the two DNA analysis techniques used until the late 1990s one required a large biological sample in good condition; the other could type small, degraded samples but did not identify suspects as precisely.

Both methods had drawbacks, according to Lynn McIntyre, lab manager of the Seattle Crime Laboratory. It was difficult to use the first method because most forensic samples are very small, she says, since suspects often get rid of obvious blood stains leaving only the evidence they don't notice. The other method, used on smaller samples, would generate DNA profiles with 1 in 2,500 to 10,000 odds that someone else had the same profile. Not very precise.

The latest form of typing, however, known as short-tandem repeats (STR), can recover DNA easily from small even trace amounts of any bodily fluid.

"I used to say, if you can see it, we can type it," McIntyre says. "Now I just say, we don't need to see it. We just need to try it."

STR typing is also more precise and quicker than older methods. On high-priority cases detectives can get test results in hours rather than weeks. And technicians can match a person's DNA genotype almost exactly.

"We don't like to call it an identity, but [with statistics like 1 in a quadrillion] it comes pretty darn close," says McIntyre.

Once the police have their profile, they turn to the National DNA Index (NDIS), a database managed by the FBI that enables states to cross-check their profile against those of nearly 1.5 million known felons and nearly 50,000 unknown crime scene profiles.

Created in October 1998 to help give local and state laboratories a way to electronically compare and share DNA data,  NDIS now works with 47 participating states, as well as Puerto Rico and the District of Columbia. It has made approximately 6,000 matches in its four-year history, an average of more than four hits a week.

Members of Seattle's cold case squad uploaded their unknown DNA profile to the system last June. They didn't get a hit then, but that September a Key West probation officer ordered one of his parolees to submit for DNA testing, in accordance with Florida law.

"Our state searches automatically every week for suspect profiles," said Mizsell. "So within a week of the suspect going [into the database] this match was made with this man from Florida."

And after nearly a decade of not knowing, police finally had a name.

One piece of the puzzle

Still, the Zapata case was far from solved. Members of law enforcement who work with DNA are careful to emphasize that it is just another piece of evidence that needs to be folded into the whole. While DNA can identify a suspect, it does not tell detectives how or why the crime was committed.

"Scientifically [DNA typing] is irrefutable," says Lisa Kreeger, DNA program director for American Prosecutors Research Institute, which educates prosecutors on how to use DNA. "I don't know of a single case where a match has been proved wrong. But we don't convict a person just because they're at a certain place at a certain time."

In prosecutions that use DNA evidence it is important to learn whether the defendant's history is consistent with the crime, says Kreeger.

In the month following Mezquia's DNA match, Seattle investigators researched his background to understand how his DNA came to rest on Mia Zapata. According to court papers, Mezquia was convicted of aggravated battery of a woman who was seven months pregnant in 1997, second-degree assault in 1986, battery of a spouse in 1989, and assault to commit rape in 1990.

And thanks to a speeding ticket and an indecent exposure complaint that was traced to a car Mezquia owned, Seattle police can link him to the neighborhood where Zapata's body was found around the time the crime was committed. Police have also interviewed three women who say they lived with Mezquia during his 1.5 years in Seattle, and they seized evidence from his home in Marathon, Fla.

Cook County prosecutors have filed extradition papers to bring Mezquia to trial in Seattle from Miami-Dade County in Florida where he is currently being held on $4 million bail, an intentionally high amount because prosecutors fear he may flee to Cuba, which has no extradition treaty with the U.S. He is contesting extradition, but a spokesman for the Seattle prosecutor's office said they foresaw no problems.

Mezquia has admitted living in Seattle in 1993 but denied all knowledge of Mia Zapata or her murder.

Although many of Zapata's friends have reportedly already celebrated the arrest, Kreeger cautions that no case is ever a sure thing, even with DNA.

She cites the 1995 O.J. Simpson trial as a case in which a jury ignored DNA testing. In that case, blood consistent with Simpson's DNA was found at the crime scene and blood consistent with his murdered wife's was found in his Ford Bronco and inside his home. But jurors were swayed by the defense's argument that the evidence could have been planted by police or contaminated by sloppy practices by the Los Angeles Crime Laboratory. They found the former football great not guilty.

More recently, Michael Porter's DNA was found on a Marlboro cigarette inside the Florida apartment of a rape victim, seemingly contradicting his testimony that he had never entered the room. His defense argued at trial that Porter did smoke that brand but that someone could have tracked the stub in on their shoe. He was acquitted in November 2002.

"There is no guarantee that jurors will accept evidence that the prosecutor knows to be reliable," says Kreeger. "It happens too frequently that juries reject evidence for any [case] to be a slam dunk."